In this post we want to show how to make a light streaks effect starting from HBO’s True Detective one. In the scene we focused, the main character is driving his car and he has some flashbacks or visions which make him see street lights contrails and light streaks coming toward him.
In order to replicate this scene we have to make two different effects, one for the light contrails and one for light strokes.
The replication of this effect is quite simple, because After Effects offers us a useful and perfect preset. After importing our video, we just apply a CC Time Blend FX from the Effect menu.
This effect acts directly on the light shot in the background video.
To increase the “Accumulation” is necessary to show the contrails on the lights, we decided to add a keyframe around 2 seconds and increase it gradually from 0 to 87,4.
to replicate the light streaks effects we need to use an external plugin: the Trapcode Particular effect. This plugin let us obtain the desired effect in an easier and more realistic way. Moreover it menage a 3D camera integration, which is very important for our purpose.
So, now we just have to add a new solid with a right click on the timeline and apply to it Effect > Trapcode > Particular
What we see now is something like that, not at all what are we looking for:
In the Emitter panel we should set all the Velocity parameter to 0, in order to make the particles closer each other.
In the Particle panel, instead, we must change many parameters. The most important one for us is the Particle Type. It set the shape of the particles that compose the streak: we select Streaklet which is made to our purpose. The other parameters we changed are set like this in order to make the streak harmonize with the background, so they could change based on what your video needs.
Now the aspect of our composition is something like that: a fixed light in the middle of the scene.
We want to animate it and make it come towards the viewer and so we need a Null object (New > Null Object).
It is very important to select the highlighted cube: through it we enable the 3D Layer that allow our object to navigate in all the three dimensions. Now we can see that the Position settings show also the Z axis and we are able to move our null object creating a path using Keyframes.
On the created Keyframes we have to change the interpolation (right click on the keyframes > keyframes Interpolation) and choose Bezier from the combobox. This procedure creates a smooth path, giving the light streak a soft motion but without too much sharp edges.
Now we have to associate the null object motion to the steak one. We can just add an expression (Animation > add expression) on the following two parameters of the solid:
Particular > Emitter > PositionXY and Particular > Emitter > PositionZ. On both of them, we just must drag and drop the snail on the null object Position parameter previously set and, only for the Z axis, change the array index from 0 (that indicate the X value) to 2 in order to have:
Now our streak follow the null object! We can add some Glow to make it similar to a real light or change the Particular > Particle parameters based on the necessity. To conclude we can duplicate both the streak and the null object, change the null object path and make many light streaks in order to better reproduce the original video.